opencode: fix failed to change directory error

Fixed the `failed to change directory` error when running
`opencode` without arguments. The issue is related to the
update of bun 1.2.20 to 1.2.21 where they introduced the
`--compile-exec-argv` flag which has to be set to `"--"`
to achieve the same behavior as before (see the changelog
https://github.com/sst/opencode/issues/462#issuecomment-3261213732).

pkgs/by-name/op/opencode/package.nix

@@ -135,6 +135,7 @@ stdenvNoCC.mkDerivation (finalAttrs: {
       --define OPENCODE_TUI_PATH="'${finalAttrs.tui}/bin/tui'" \
       --define OPENCODE_VERSION="'${finalAttrs.version}'" \
       --compile \
+      --compile-exec-argv="--" \
       --target=${bun-target.${stdenvNoCC.hostPlatform.system}} \
       --outfile=opencode \
       ./packages/opencode/src/index.ts \